The swift fox (Vulpes velox) is a small light orange-tan fox around
the size of a domestic cat found in the western grasslands of North
America, such as Montana, Colorado, New Mexico, Kansas, Oklahoma[3]
and Texas.[1] It also lives in Manitoba, Saskatchewan and Alberta in
Canada, where it was previously extirpated.[2] It is closely related
to the kit fox and the two species are sometimes known as subspecies
of Vulpes velox because hybrids of the two species occur naturally
where their ranges overlap.
The swift fox lives primarily in short-grass prairies and deserts. It
became nearly extinct in the 1930s as a result of predator control
programs, but was successfully reintroduced later. Currently, the
conservation status of the species is considered by the IUCN as Least
Concern owing to stable populations elsewhere.[2]
Like most canids, the swift fox is an omnivore, and its diet includes
grasses and fruits as well as small mammals, carrion, and insects. In
the wild, its lifespan is three to six years, and it breeds once
annually, from late December to March, depending on the geographic
region. Pups are born anywhere from March to mid-May, and are weaned
at six to seven weeks old.
The swift fox is closely related genetically to the kit fox (Vulpes
macrotis), but occupies a different geographical range. The two have
historically been regarded as different species for reasons basically
related to size: the kit fox is slightly smaller than the swift fox,
and the former has a narrower snout. However, hybrids between the two
occur naturally where their ranges overlap, and some mammalogists
classify the two as subspecies of a single species, usually treated as
Vulpes velox (with the swift fox being described as V. velox velox and
the kit fox as V. velox macrotis).[4] The molecular genetics evidence
is not conclusive however, and some of those who have used it continue
to treat the swift fox and kit fox as separate species.[5]

Description[edit]
The swift fox has a dark, grayish, tan coloration that extends to a
yellowish tan color across its sides and legs. The throat, chest, and
belly range from pale yellow to white in color. Its tail is
black-tipped, and it has black patches on its muzzle. Its ears are
noticeably large. It is about 12 inches (30 cm) in height,
and 31 inches (79 cm) long, measuring from the head to the
tip of the tail, or about the size of a domestic cat. Its weight
ranges from around five to seven pounds.[6] Males and females are
similar in appearance, although males are slightly larger.[7]
Distribution and habitat[edit]
The swift fox lives in short-grass prairies and western grassland .
They form their dens in sandy soil on open prairies, in plowed fields,
or along fences.[7] It is native to the Great Plains region of North
America, and its range extends north to the central part of Alberta
and Saskatchewan, Canada, and south to Texas. It reaches from western
Iowa to Colorado, Kansas, Wyoming, Nebraska, and Montana.[6]
Conservation status[edit]
The swift fox was once a severely endangered species, due to predator
control programs in the 1930s that were aimed mostly at the gray wolf
and the coyote.[7] The species was extirpated from Canada by 1938,[2]
but a reintroduction program started in 1983[8] has been successful in
establishing small populations in southeast Alberta and southwest
Saskatchewan, despite the fact that many reintroduced individuals do
not survive their first year.[7] Nonetheless, by 1996, 540 foxes had
been released around the Alberta-Saskatchewan border and Milk River
Ridge areas, parts of the species' original native range.[9] Four
years later, those introduced foxes had tripled in number, making the
program one of the most successful endangered species reintroduction
programs in the world.[10] In May 1999, the Species at Risk Act listed
the swift fox as an endangered species in Canada, giving the species
further protection for growth.[11] A small, but stable and growing
population continues to live freely in the southeastern regions of
Alberta, and southwestern regions of Saskatchewan.
Exact population numbers of the swift fox are unknown, but it is known
that they currently inhabit only 40% of their historic range.[6] In
addition to its populations in Canada, there are also swift fox
populations in the United States, ranging from South Dakota to Texas.
In 1995, the U.S. Fish and Wildlife Service determined that the fox
warranted an endangered listing, but other higher priority species
precluded its listing.[12] This prompted state wildlife agencies
within the fox's range to create the Swift Fox Conservation Team,
which worked to implement better swift fox management and monitoring
programs.[12] Populations in the United States are stable in the
central part of its range,[7] and it is not considered endangered in
the United States. The IUCN Red List characterizes it as of Least
Concern.[2]
Behavior[edit]

A swift fox napping during the day in a zoo.

In the wild, the swift fox usually lives 3–6 years, but may live up
to 14 years in captivity. It is primarily nocturnal, spending only
evenings and nighttime above ground in the summer. Daytime activities
are usually confined to the den, but it has been known to spend the
warm midday period above ground during the winter.[7] The swift fox is
more heavily dependent on its den than most North American canids,
using them as shelter from predators. These dens are usually
underground burrows that are two to four meters in length.[7] It has
been known to run very fast, at speeds of over 50 km/h
(30 mph).[7] or up to 60 km/h (40 mph) [13] The coyote
is the swift fox's main predator, but often chooses not to consume the
swift fox.[14] Other predators include the badger, golden eagle, and
bobcat.[14] It is also vulnerable to trapping and poisoning, as well
as death on highways.[15]
Reproduction[edit]
Swift foxes are a socially monogamous species, although multiple
breeding strategies have been observed.[16] The adult swift fox's
breeding season varies with region. In the southern United States, it
mates between December and February with pups born in March and early
April, while in Canada, the breeding season begins in March, and pups
are born in mid-May. The male swift fox matures and may mate at one
year, while the female usually waits until her second year before
breeding. Adults live in pairs, and although some individuals mate for
life, others choose different partners each year. Gestation takes
around 51 days, and four to five kits are born.[6][7]
The swift fox only has one litter annually, but may occupy up to
thirteen dens in one year, moving because prey is scarce or because
skin parasites build up inside the den. Sometimes it makes other
burrows from other bigger animals, even though it is completely
capable of digging one on its own. Pups are born in the den and
typically remain there for approximately one month. A newborn pup's
eyes and ears remain closed for ten to fifteen days, leaving it
dependent on the mother for food and protection during this time. It
is usually weaned around six or seven weeks old and remains with its
parents until fall.[7] Recent research has shown that social
organization in the swift fox is unusual among canids, since it is
based on the females.[17] Females maintain territories at all times,
but males emigrate if the resident female is killed or removed.[17]
Diet[edit]
Like most canids, the swift fox is an omnivore. Rabbits, mice, ground
squirrels, birds, insects and lizards are staples.[6] Grasses and
fruits round out its diet. However, like any efficient forager, the
swift fox takes advantage of seasonal foods.[7] During the summer,
adults eat large amounts of insects, including beetles and
grasshoppers, and feed their young with larger prey items. Deer and
other carrion killed by other animals may also be important food
sources.
References[edit]